Levulinic acid is a well-known product of hexose acid hydrolysis, and can be inexpensively obtained from cellulose feedstocks. Consequently, it is an attractive starting material in producing many useful 5-carbon compounds and their derivatives. For example, N-cyclohexyl-2-pyrrolidone is used as a solvent or intermediate in many industrial applications, including the electronics industry (photo-resist stripping solutions), industrial cleaners, oilgas well maintenance, and fiber dyeing. N-[2-hydroxyethyl]-2-pyrrolidone is useful in industrial cleaning, printing inks, and gasoline and oil additives. N-octyl-2-pyrrolidone is useful, for example, in the manufacture of agricultural products, as a detergent and dispersant, in industrial and metal cleaners, in printing inks and in fiber dyeing.
U.S. Pat. No. 3,337,585 discloses a process for preparing 5-methyl-1-alkyl-2-pyrrolidone utilizing levulinic acid and a primary alkyl amine at a temperature of 50° C. to 350° C. under carbon monoxide at a pressure of 1.0 to 101 MPa. Additional potential primary amines include alkylene diamines, aryl amines and cycloalkyl amines. Nitriles (alkyl cyano compounds) are not used. U.S. Pat. No. 3,235,562 describes a vapor phase process for producing lactams by the reductive amination of oxo carboxylic acid compounds. Volatile alkyl or aryl primary amines may be used; nitriles are not used. Candeloro and Bowie (Aust. J. Chem., 1978, 31:2031-2037) describe a process for producing 5-methyl-2,3-dihydro-1-H-benzazepin-2-one and 5-(2-methyl-5-oxo-1-phenylpyrrolidin-2-yl)4-oxo-N-phenylpentanamide by reacting levulinic acid with aniline under a nitrogen atmosphere.
An efficient and low cost process for the production of aryl, alkyl and cycloalkyl pyrrolidones would be advantageous.